Which symptom is NOT associated with insufficient exhaust gas recirculation?

Insufficient exhaust gas recirculation (EGR) typically leads to several noticeable symptoms due to the engine's increased tendency to experience higher combustion temperatures, which can elevate emissions and affect performance dynamics.

The option regarding increased CO2 emissions is not directly associated with insufficient EGR. In fact, a properly functioning EGR system is designed to reduce nitrogen oxide (NOx) emissions by recirculating a portion of the exhaust gas back into the combustion chamber, thereby cooling the combustion temperature. If EGR is insufficient, while NOx emissions may increase, the actual CO2 emissions would not necessarily rise due to EGR; instead, the combustion process may become less efficient, which can increase unburned hydrocarbons and other pollutants but not CO2 specifically from this deficiency.

On the other hand, symptoms such as spark knock, stalling, and surging at cruise can all occur with insufficient EGR. Spark knock can arise because higher combustion temperatures can lead to premature ignition. Stalling can happen due to the inconsistency in combustion processes. Surging at cruise can occur when the engine experiences irregularities due to insufficient exhaust gas flow and improper remapping of air-fuel mixtures. Thus, these symptoms relate closely to the effects of a malfunction